EP1853641B1 - Reinforced polyurethane-urea elastomers and the use thereof - Google Patents

Description

The invention relates to reinforced polyurethaneurea elastomers having a certain urea content and a specific urethane content and also to surface-area polyurethane molded articles obtainable therefrom having improved toughness and improved shrinkage properties and to the use thereof.

The preparation of polyurethaneurea elastomers by reacting NCO semiprepolymers with mixtures of aromatic diamines and compounds having relatively high molecular weight hydroxyl or amino groups is known and disclosed, for example, in US Pat EP-A 656 379 described. These polyurethane elastomers show improved mechanical properties. In order to achieve certain mechanical properties in the molded articles produced therefrom, reinforcing materials must be added to the reaction components, which in particular improves thermomechanical properties and significantly increases the flexural modulus of elasticity. However, in the case of multiple thermal loading of these moldings, which may occur, for example, as a result of a plurality of paint curing steps, it is observed that the shrinkage values of such moldings can be impaired.

In EP-A 656381 are described reinforced polyurethane ureas consisting of a polyol component containing a polyether polyol having an ethylene oxide content of 50-100 wt .-% and an aromatic diamine such as DETDA, and a prepolymer of a uretonimine modified MDI and a polyether triol with 10-85 wt. -% EO are produced.

However, it is desirable to have as low a shrinkage value as possible and, in particular, a constant shrinkage, even in the case of repeated thermal aftertreatment processes, in order to finally be able to produce accurately fitting parts. Another important property is the flexural strength of the parts during demoulding.

The object was therefore to provide polyurethane elastomers which have low shrinkage or shrinkage under considerable thermal stress and high toughness during demolding.

It has now surprisingly been found that certain polyurethaneurea elastomers equipped with reinforcing materials ensure trouble-free processing with regard to the production of tough, flat moldings with perfect behavior with regard to dimensional stability even under considerable stress by thermal aftertreatment and have low shrinkage values overall.

• A1) aromatischen Diaminen, die zumindest in jeweils einer ortho-Stellung zu den Aminogruppen einen Alkylsubstituenten aufweisen,
• A2) einer aliphatischen Reaktionskomponente bestehend aus mindestens einem Hydroxyl- und/oder primäre Aminogruppen aufweisenden Polyetherpolyol der Molmasse 500 bis 18 000,
• A3) gegebenenfalls aliphatischen Aminen,
• A4) Verstärkungsstoffen sowie
• A5) gegebenenfalls Katalysatoren und/oder Zusatzstoffen
• A6) gegebenenfalls einem Metallsalz als Trennmittel

sowie einem Prepolymer als B-Komponente erhältlich aus

• B1) einer Polyisocyanatkomponente bestehend aus einem verflüssigten Polyisocyanat oder Polyisocyanatgemisch der Diphenylmethanreihe, ausgenommen durch partielle Carbodiimidisierung der Isocyanatgruppen von 4,4'-Diisocyanatodiphenylmethan, dessen Gemischen mit 2,2'- und insbesondere 2,4'-Diisocyanatodiphenylmethan und Gemischen dieser Diisocyanatodiphenylmethan-Isomeren mit ihren höheren Homologen modifizierte Di- und/oder Polyisocyanate, und
• B2) einer Polyolkomponente mit einer mittleren Molmasse von 500 bis 18 000, bestehend aus mindestens einem, gegebenenfalls organische Füllstoffe enthaltenden Polyetherpolyol,

dadurch gekennzeichnet, dass die Komponente A2) eine Funktionalität von 2 bis 8 sowie einen Ethylenoxid-Gehalt von 40-100 Gew.-% und einen Alkyloxiran-Gehalt von 0-60 Gew.-% und die Komponente B2) eine Funktionalität von 2 bis 8 und einen Ethylenoxid-Gehalt von < 40 Gew.-% und einen Alkyloxiran-Gehalt von > 60 Gew.-% aufweist, wobei die A-Komponente und die B-Komponente in einem solchen stöchiometrischen Mengenverhältnis umgesetzt werden, dass die Isocyanatkennzahl des erhaltenen Elastomeren im Bereich von 80 bis 120 liegt und die über die B-Komponente eingebrachte Polyolkomponente B2) 10 bis 90 Mol-% des Urethananteils darstellt. Bevorzugt werden verstärkte Polyurethanharnstoff-Elatomere mit einem Harnstoffanteil von 75 bis 95 Mol-% und einem Urethananteil von 5 bis 25 Mol-%, bezogen auf Mol-% eines NCO-Äquivalents.The present invention relates to reinforcing agent polyurethaneurea elastomers having a urea content in the range of 70 to 95 mol% and a urethane content in the range of 5 to 30 mol%, based on mol% of an NCO equivalent, obtainable by reacting a Reaction mixture of an A component consisting of

• A1) aromatic diamines which have an alkyl substituent at least in each case in an ortho position to the amino groups,
• A2) an aliphatic reaction component consisting of at least one hydroxyl and / or primary amino-containing polyether polyol of molecular weight 500 to 18,000,
• A3) optionally aliphatic amines,
• A4) reinforcing materials as well
• A5) if appropriate, catalysts and / or additives
• A6) optionally a metal salt as a release agent

and a prepolymer available as B component

• B1) a polyisocyanate component consisting of a liquefied polyisocyanate or polyisocyanate mixture of the diphenylmethane series, except by partial carbodiimidization of the isocyanate groups of 4,4'-diisocyanatodiphenylmethane, its mixtures with 2,2'- and especially 2,4'-diisocyanatodiphenylmethane and mixtures of these diisocyanatodiphenylmethane isomers with their higher homologues modified di- and / or polyisocyanates, and
• B2) a polyol component having an average molecular weight of 500 to 18,000, consisting of at least one, optionally organic fillers containing polyether polyol,

characterized in that the component A2) has a functionality of 2 to 8 and an ethylene oxide content of 40-100 wt .-% and an alkyloxirane content of 0-60 wt .-% and the component B2) has a functionality of 2 to 8 and an ethylene oxide content of <40 wt .-% and an alkyloxirane content of> 60 wt .-%, wherein the A component and the B component are reacted in such a stoichiometric amount ratio that the isocyanate index of the obtained Elastomers in the range of 80 to 120 and introduced via the B component polyol component B2) represents 10 to 90 mol% of the urethane content. Preference is given to reinforced polyurethaneurea elastomers having a urea content of from 75 to 95 mol% and a urethane content of from 5 to 25 mol%, based on mol% of an NCO equivalent.

Another object of the invention are polyurethane body / parts of the polyurethaneurea elastomers according to the invention with good dimensional stability after thermal treatment and high breaking strength after demolding.

It is further preferred that the A component and the B component are reacted in an amount such that the isocyanate index of the resulting elastomer is preferably in the range of 90 to 115 and introduced via the B component polyol component B2) from 30 to 85 represents% of the urethane content.

As reinforcing agents A4) such reinforcing materials are preferably used, which are inorganic in nature and have a platelet and / or needle structure. In particular, these are silicates of the II. And III. Main group of the periodic table, such as wollastonite-type calcium silicate and mica or kaolin-type aluminum silicates. Such silicate reinforcing materials are known under the name group, ring, chain or tape silicates, for example in Hollemann-Wiberg, W. de Gruyter Verlag (1985) 768-778 described.

These reinforcing materials have a diameter or a board height or thickness of 2 to 30 .mu.m and a length extension of 10 to 600 .mu.m and have a length / diameter quotient of in the range 5: 1 to 35: 1, preferably 7: 1 to 30: 1, lies. The diameter of spherical portions is 5 to 150, preferably 20 to 100 microns.

The stated reinforcing materials are usually added in amounts of 10 to 35 wt .-%, preferably 10 to 30 wt .-%, based on the total amount of the components A and B.

Suitable components A1) are aromatic diamines which have an alkyl substituent at least in each case in an ortho position relative to the amino groups and which have a molecular weight of 122 to 400. Particularly preferred are those aromatic diamines having at least one alkyl substituent ortho to the first amino group and two alkyl substituents ortho to the second amino group each having 1 to 4, preferably 1 to 3, carbon atoms. Very particular preference is given to those which have in each case at least one ortho-position to the amino groups an ethyl, n-propyl and / or iso-propyl substituent and optionally in further ortho positions to the amino groups methyl substituents. Examples of such diamines are 2,4-diaminomesitylene, 1,3,5-triethyl-2,4-diaminobenzene and its technical mixtures with 1-methyl-3,5-diethyl-2,6-diaminobenzene or 3,5,3 ', 5'-tetraisopropyl-4,4'-diaminodiphenylmethane. Of course, the mixtures can also be used with each other. Component A1) is particularly preferably 1-methyl-3,5-diethyl-2,4-diaminobenzene or technical mixtures thereof with 1-methyl-3,5-diethyl-2,6-diaminobenzene (DETDA). ,

Component A2) consists of at least one polyether polyol having a molecular weight of 500 to 18,000, preferably 1000 to 16,000, preferably 1,500 to 15,000, having at least one aliphatically bonded hydroxyl and / or primary amino group. Component A2) has the abovementioned Functionalities. The polyether polyols can be prepared in a manner known per se by alkoxylation of starter molecules or mixtures thereof of corresponding functionality, in particular ethylene oxide and subordinated alkyloxiranes, such as propylene oxide, being used for the alkoxylation. Suitable starter or starter mixtures are sucrose, sorbitol, pentaerythritol, glycerol, trimethylene propane, propylene glycol and water. Preference is given to those polyether polyols whose hydroxyl groups consist of at least 50%, preferably at least 70%, in particular exclusively of primary hydroxyl groups. Also suitable here are those polyether polyols which optionally contain organic fillers in dispersed form. These dispersed fillers are, for example, vinyl polymers, as formed by polymerization of acrylonitrile and styrene in polyether polyols as the reaction medium (US Pat 33 83 351 . 33 04 273 . 35 23 093 . 31 10 695 , DE-PS 11 52 536 ), or to polyureas or polyhydrazides, as formed by a polyaddition reaction in polyether polyols as a reaction medium of organic diisocyanates and diamines or hydrazine ( DE-PS 12 60 142 . DE-OS 24 23 984 . 25 19 004 . 25 13 815 . 25 50 833 . 25 50 862 . 26 33 293 . 25 50 796 ).

Such polyethers are described, for example, in Kunststoffhandbuch 7, Becker / Braun, Carl Hanser Verlag, 3rd edition, 1993 ,

Furthermore, as the component A2) primary polyether polyols containing primary amino groups can be used, as described for example in EP-A 219,035 and are known as ATPE (amino-terminated polyethers).

In particular, the so-called Jeffamine ^® Texaco that, ω-diaminopolypropylene glycols are composed of α suitable as component A3).

As component A5), the known catalysts for the urethane and urea reaction can be used, such as tertiary amines or the tin (II) - or tin (IV) salts of higher carboxylic acids. Other additives include stabilizers, such as the known polyether siloxanes or release agents used. The known catalysts or additives are described for example in Chapter 3.4 of Kunststoffhandbuch 7, Polyurethane, Carl Hanser Verlag (1993), pp. 95 to 119 and can be used in the usual amounts.

As component A6) metal salts such as zinc stearate, zinc palmitate, zinc oleate, magnesium stearate can be used. These are preferably dissolved and used in component A3).

The so-called B component is an NCO prepolymer based on the polyisocyanate component B1) and the polyol component B2) and has an NCO content of 8 to 26 wt .-%, preferably 12 to 25 wt .-%, from.

The polyisocyanates B1) are optionally polyisocyanates or polyisocyanate mixtures of the diphenylmethane series liquefied by chemical modification. The term "polyisocyanate of the diphenylmethane series" represents the generic term for all polyisocyanates, as they are formed in the phosgenation of aniline / formaldehyde condensates and present in the phosgenation as individual components. The term "diphenylmethane series polyisocyanate mixture" means any mixtures of polyisocyanates of the diphenylmethane series, i. for example, for the said phosgenation products, for the mixtures obtained in the distillative separation of such mixtures as distillate or distillation residue and for any mixtures of polyisocyanates of the diphenylmethane series.

Typical examples of suitable polyisocyanates B1) are 4,4'-diisocyanatodiphenylmethane, mixtures thereof with 2,2'- and especially 2,4'-diisocyanatodiphenylmethane, mixtures of these diisocyanatodiphenylmethane isomers with their higher homologs, as used in the phosgenation of aniline / Incurred formaldehyde condensates, except by partial carbodiimidization of the isocyanate groups of said di- and / or polyisocyanates modified di- and / or polyisocyanates, or any mixtures of such polyisocyanates.

Particularly suitable as component B2) are the polyether polyols corresponding to this definition or mixtures of such polyhydroxyl compounds. Suitable examples are suitable polyether polyols which optionally contain organic fillers in dispersed form. These dispersed fillers are, for example, vinyl polymers, as are formed, for example, by polymerization of acrylonitrile and styrene in the polyether polyols as reaction medium (US Pat 33 83 351 . 33 04 273 . 35 23 093 . 31 10 695 , DE-PS 11 52 536 ) or polyureas or polyhydrazides, as they are formed by a polyaddition reaction in the polyether polyols as a reaction medium of organic diisocyanates and diamines or hydrazine ( DE-PS 12 60 142 . DE-OS 24 23 984 . 25 19 004 . 25 13 815 . 25 50 833 . 25 50 862 . 26 33 293 or 25 50 796 ). In principle, polyether polyols of the type already mentioned above under A2) are suitable as component B2), provided that they correspond to the last-mentioned characteristic data.

The polyol component B2) has an average molar mass of preferably 1000 to 16,000, in particular 2000 to 16,000, with an average hydroxyl functionality of 2 to 8, preferably 3 to 7.

For the preparation of the NCO semiprepolymer B) are preferably the components B1) and B2) in such proportions to the reaction (excess NCO) that NCO semiprepolymers result in the above NCO content. The reaction in question is generally carried out within the temperature range of 25 to 100 ° C. In the preparation of the NCO semi-prepolymers, the total amount of the polyisocyanate component B1) is preferably reacted with preferably the total amount of the component B2) intended for the preparation of the NCO semiprepolymers.

The preparation of the elastomers according to the invention is carried out by the known reaction injection molding technique (RSG method, "RIM-process"), as described for example in DE-AS 2 622 951 ( US 4 218 543 ) or DE-OS 39 14 718 is described. The proportions of components A) and B) in this case correspond to the stoichiometric ratios with an NCO index of 80 to 120. The amount of introduced into the mold reaction mixture is also calculated so that the moldings have a density of at least 0.8, preferably 1.0 to 1.4 g / cm ³ . Of course, the density of the resulting shaped articles depends to a great extent on the type and proportion by weight of the filler used. In general, the molded parts according to the invention are microcellular elastomers, ie they are not real foams which are visible to the naked eye. This means that optionally used organic blowing agents exert less the function of a true propellant than the function of a superplasticizer.

The starting temperature of the introduced into the mold reaction mixture of the components A) and B) is generally from 20 to 80, preferably 30 to 70 ° C. The temperature of the mold is generally from 30 to 130, preferably 40 to 80 ° C. The molds used are those of the type known per se, preferably of aluminum or steel or metal-sprayed epoxy tools. To improve the release properties, the inner walls of the mold used can optionally be coated with known outer mold release agents.

The moldings / moldings produced in the mold can generally be removed from the mold after a mold life of 5 to 180 seconds. Optionally, the demolding annealing at a temperature of about 60 to 180 ° C for a period of 30 to 120 minutes.

The reinforced polyurethaneurea elastomers according to the invention are used for the production of moldings / molded parts in processes known per se.

The resulting, preferably flat moldings are particularly suitable for the production of in particular painted components in the vehicle sector, e.g. flexible automotive aprons or flexible body elements, such as doors and tailgates or fenders of automobiles.

The invention will be explained in more detail with reference to the following examples.

Examples raw materials Semiprepolymer 1

• NCO-Gehalt nach 2 Stunden: 18,1 %

976 parts by weight of 4,4'-diisocyanatodiphenylmethane are reacted at 90 ° C. with 724 parts by weight of the polyetherpolyol 2 of the functionality 6.

• NCO content after 2 hours: 18.1%

Semiprepolymer 2

• NCO-Gehalt nach 2 Stunden: 18,2 %

1121 parts by weight of 4,4'-diisocyanatodiphenylmethane are reacted at 90 ° C. with 779 parts by weight of the polyether polyol 1 of the functionality 3.

• NCO content after 2 hours: 18.2%

Polyol 1

Polyether polyol of OH number 37, prepared by alkoxylation of glycerol as a starter in the ratio of 72 wt .-% of ethylene oxide and 18 wt .-% of propylene oxide with predominantly primary OH groups.

Polyol 2

Polyether polyol of OH number 28, prepared by propoxylation of the hexafunctional starter sorbitol with propylene oxide and subsequent ethoxylation in the ratio 83:17 with predominantly primary OH groups.

DETDA

Mixture of 80% by weight of 1-methyl-3,5-diethyl-2,4-diaminobenzene and 20% by weight of 1-methyl-3,5-diethyl-2,6-diaminobenzene

DABCO 33 LV

Solution of 1,4-diazabicyclo [2.2.2] octane in dipropylene glycol (Air Products)

Jeffamine D400

Polyoxypropylene diamine (Texaco)

DBTDL

dibutyltindilaurate

wollastonite

Tremin 939-955 of Fa. Quarzwerke, Frechen
The processing of the formulations described below was carried out by reaction injection molding. The A and B components are pressed in a Hochdruckdosiergerät after intensive mixing in a positively controlled mixing head in a heated plate mold a mold temperature of 60 ° C the dimensions of 300 x 200 x 3 mm on a Dustalkkenanguss.

The temperature of the A component was 60 ° C, the temperature of the B component was 50 ° C. It was demolded after 30 seconds.

The mechanical values were measured after annealing in a convection oven (45 min. At 160 ° C) and subsequent storage (24 hours).

Before each series, the tool was treated with the mold release agent Acmos 36-5130 from Acmos Bremen.

The quantities in the table are in parts by weight. <b><u> Table 1 </ u></b> example 1 2 (comparison) Polyol 1 52.5 - Polyol 2 - 52.5 DETDA 42.0 42.0 Zn stearate 2 2 Jeffamine D400 3 3 Dabco 33 LV 0.3 0.3 DBTDL 0.2 0.2 Sum of A components 100.0 100.0 wollastonite 64.2 63.6 Semiprepolymer 1 127.6 - Semiprepolymer 2 - 125.5 Wollastonite in the elastomer [% by weight] 22 22 index 105 105 Break by bending by hand No Yes Tread resistance of the bent plate: number of treads without breakage a) directly after demolding 8th* 0 b) after annealing at 160 ° C / 45 min > 10 > 10 Shrinkage values (1 / q) [%]: at RT 0.36 / 1.0 0.58 / 1.1 after 1st heat treatment (160 ° C / 45 min) 0.51 / 1.3 0.67 / 1.3 after 2nd annealing (160 ° C / 45 min) 0.53 / 1.3 0.87 / 1.4 Elongation at break DIN 53504 [%] 160 110 Flexural modulus ASTM 790 [MPa] 2100 1680 HDT ISO 75-1 / 75-2 [° C] 185 175 * on the 9th kick slight tears occurred
1 = in the longitudinal direction
q = transverse to the longitudinal direction

The polyurethaneurea elastomer 1 shows over the elastomer 2 (comparative experiment) important advantages in terms of mechanical properties, such as the tremendous impact resistance already in the demoulding of the test specimens in the unannealed state. Also advantageous is the only slight change in the shrinkage on renewed annealing at 160 ° C for 45 minutes. In the comparative experiment, the change is 0.2% in the longitudinal direction; that is, a 1 m long molded article is 2 mm shorter after being annealed again.

Claims (3)

1. Reinforced polyurethaneurea elastomers with a urea share in the range 70 to 95 mol.% and a urethane share in the range 5 to 30 mole.%, with respect to mol.% of a NCO equivalent, obtainable by reacting a reaction mixture comprising an A-component consisting of

   A1) aromatic diamines which each have an alkyl substituent in at least one ortho-position to the amino groups,

   A2) an aliphatic reaction component consisting of at least one polyether polyol which contains hydroxyl and/or primary amino groups and has a molecular weight of 500 to 18 000,

   A3) optionally, aliphatic amines,

   A4) reinforcement substances and

   A5) optionally, catalysts and/or additives,

   A6) optionally, a metal salt as a mould release agent

   as well as a prepolymer as a B-component obtainable from

   B1) a polyisocyanate component consisting of a liquefied polyisocyanate or polyisocyanate mixture from the diphenylmethane series other than di- and/or polyisocyanates modified by partial carbodiimidisation of the isocyanate groups of 4,4'-diisocyanatodiphenylmethane, its mixtures with 2,2'- and in particular 2,4'-diisocyanatodiphenylmethane and mixtures of these diisocyanatodiphenylmethane isomers with their higher homologues, and

   B2) a polyol component with an average molecular weight of 500 to 18 000, consisting of at least one polyether polyol which optionally contains organic fillers,

   characterised in that component A2) has a functionality of 2 to 8 and an ethylene oxide content of 40-100 wt.% and an alkyloxirane content of 0-60 wt.% and component B2) has a functionality of 2 to 8 and an ethylene oxide content of <40 wt.% and an alkyloxirane content of >60 wt.%, wherein the A-component and the B-component are reacted in a stoichiometric ratio by weight such that the isocyanate index of the elastomer obtained is in the range 80 to 120 and polyol component B2) introduced via the B-component represents 10 to 90 mol.% of the urethane share.
2. Polyurethane moulded items/parts made from reinforced polyurethaneurea elastomers in accordance with Claim 1.
3. Use of the moulded parts/items in accordance with Claim 2 to produce lacquered components for the vehicle industry.